The invention relates to a bicycle frame in accordance with the preamble of claim 1, and coupling means in particular for the connection of a like bicycle frame.
In recent years, there has been an increasing tendency among automobile manufacturers to offer brand specific products in addition to the vehicles. One particular focal point rests on high-value bicycles offered by the traders under their respective brands, who thus enter into direct competition with bicycle traders. In terms of their construction, the bicycles are generally adapted to the one target group the respective automobile manufacturer desires to reach with his vehicles. Thus, sports car manufacturers as a rule offer very sporting racing bikes and mountain bikes, whereas other enterprises concentrate on touring or trekking bikes. The manufacturers additionally offer carrier systems constructively adapted to the automobile type and to the bicycle.
Most recently, leading automobile manufacturers sell so-called xe2x80x9croadstersxe2x80x9d, i.e., two-seater open-tops and convertibles possessing a comparatively limited trunk volume and conceived essentially with a view to maximum driving fun, and in a lesser degree to maximum transport capacity. The like roadsters are as a general rule designed as convertibles, or with removable or retractable roof elements, whence fastening of the roof rack systems poses problems. These vehicles have a very compact design so that roof transport of a large-size bicycle is not in agreement with aesthetic standards. There is therefore a desire to design the bicycles with disassemblable frames to enable easier roof rack transport.
German utility model No. 295 13 779 discloses a sports bicycle having a disassemblable carbon frame separable through the intermediary of a insertion connection, with fixation of the frame parts being effected by means of a quick-lock connection. In this insertion connection, an end portion of the one frame part is inserted into the correspondingly fashioned end portion of the other frame part, with the provided fit having to ensure joining together of the frame parts at low expenditure of force on the one hand, and precise guidance of the frame components relative to each other on the other hand.
In such insertion systems there is, however, a possibility of soiling adhering in the overlap region to cause difficulty in assembling or disassembling the frame parts. Such soiling may damage the insertion fit to detract from the lifetime of the frame. Another problem is that this insertion fit must be produced with maximum precision, requiring considerable expenditure in terms of device and production technology.
In these high-value bicycles the transfer elements for actuation of the gear-shift mechanism and the rear wheel brake are customarily routed in the frame to avoid degradation of the aesthetic impression of the frame by Bowden wire guides etc. Disassemblable bicycles present a problem in that these actuating means (Bowden wires) extend through the plane of separation of the frame parts and must therefore be provided with corresponding coupling means. The above mentioned publication proposes in this respect to couple the Bowden wires by means of a hydraulic system. As an alternative, a mechanically acting lever mechanism 15 disclosed, wherein the Bowden wires are linked to a respective pivoting lever in each frame part, and the rotating movements of the levers are used for transferring the actuation forces. Realisation of either construction variant requires considerable expense in terms of device technology which quite considerably influences the price of the frame. One further problem resides in the fact that the sophisticated coupling systems are prone to soiling and did not present the necessary reliability in exacting, long-term operation.
From-FR-A-1514213 a disassemblable bicycle frame is known, wherein a down tube of the frame is separable into two frame parts along a plane of separation, and from which the present invention starts out. What is provided are connecting means for releasably joining together the two frame parts at the plane of separation, with the connecting means including an abutment with a supporting member which extends from; one frame part through a plane containing the plane of separation as far as a bearing in the other frame part and presents tensioning means for bracing the two frame parts, such that the supporting member is supported against the bearing, and the two frame parts contact each other by their front faces.
Herein the plane of separation essentially extends perpendicularly with respect to the longitudinal axis of the down tube. This circumstance, and the chosen design of the connecting means having the form of a simple tension bracket, have the effect that this known bicycle frame is only suited for low strains. Particularly for the use in so-called ATBs (all-terrain bikes) or mountain bikes it may be presumed to be utterly insufficient.
In contrast, the invention is based on the object of furnishing a disassemblable frame for a bicycle and a coupling system, in particular for such disassemblable frames, enabling a reliable connection of the structural components at minimum expense in terms of device technology.
This object is attained through the features of claim 1 as regards the frame, and through the features of claim 20 with respect to the coupling means.
Accordingly, in the bicycle frame in accordance with the invention the plane of separation extends through the down tube in such a manner as to have an inclination of approximately 45xc2x0 relative to the center axis of the down tube, the supporting member is a hook fastened in a down tube portion, and the abutment is a bolt arranged in the other down tube portion, a section of which is encompassed by said hook, and the encompassing portion of the hook transfers a force component acting in the direction of the vertical axis of the bicycle to said bolt.
Hereby a high-strength connection is made possible: the separation into abutment/supporting member and tensioning means, as well as the support along the front face enable the transfer of extremely high frame forces, so that the bicycle frame satisfies even maximum demands, for example in the case of downhill contests.
The frame parts may be joined together in a particularly easy manner inasmuch as the supporting member has the form of a hook, and this hook-shaped portion is supported on a bolt. The direction of support is chosen such as to coincide with the direction of the forces introduced into the frame by the rider, whence the rider""s very weight contributes to maintaining the connection between the supporting member and the abutment. The hook-shaped design of the supporting member moreover makes it possible to perform a relative rotation of the two frame parts when the tensioning means are released, with this rotating movement being guided by engagement of the hook-shaped portion of the supporting member on the bolt.
Inasmuch as slide fits are essentially not necessary, damage to the frame fit owing to soiling is virtually impossible. The construction of the connecting means according to the invention moreover allows for easy cleaning of the structural components prior to assembly, whereby failures due to jamming etc. are prevented. As the frictional connection is established through the intermediary of the tensioning means and the abutment/supporting member, and the tensioning force may be modified through corresponding readjustment of the tensioning means, tolerances due to manufacture or wear of the joint may be compensated by readjusting the tensioning force without the fit quality being affected in any way whatsoever.
Relative rotations of the two frame parts are facilitated if the front or bearing surface of one of the frame parts is recessed in the range of the abutment such that the frame parts may be pivoted about the abutment without any collision of the front surfaces.
The tensioning means preferably include a pivotally mounted tensioning hook, the hook portion of which may be taken into engagement with a tensioning bolt fastened on the other frame component. These tensioning means may, for example, have the form of an elbow lever. It is, however, preferred to mount the tensioning hook on an eccentric shaft which may be rotated with the aid of a tensioning lever. Owing to the eccentric mounting of the tensioning hook, a predetermined tensioning force holding the two frame parts together and pressing the supporting member onto the abutment may be applied upon closing the tensioning means.
A particularly smooth planar construction is obtained if the tensioning lever may be pivoted towards the tensioning hook for locking and in the process enters into a recess on the outer surface of the frame parts such that the tensioning lever is received flush in the frame.
The frame is preferably manufactured of high-strength plastic, for example of carbon fiber, with the contact portions of the frame component and the tensioning device itself being formed in housing parts of metal preferably embedded in the plastic frame. This combination of materials one the one hand allows for a very lightweight frame, while on the other hand wear to the frame in the separating line is reduced to minimum by the metal construction of the housing part.
The couplers for connecting the actuating means for the brake and for the gear-shift mechanism are preferably formed to comprise claws which may be taken into engagement, or disengaged, by a relative movement of the two frame parts upon assembling or disassembling the frame. Owing to this positive connection of the actuating meansxe2x80x94preferably Bowden wiresxe2x80x94no additional coupling means as in the above mentioned prior art (hydraulic components, pivoting levers) need to be provided, so that the structural space for the coupling means is minimum.
The claws in accordance with the invention, which include alternately formed engagement projections and reception grooves (toothing), preferably have a lateral orientation relative to the longitudinal axis of the actuating means (Bowden wire), so that the coupling/uncoupling movement takes place not in the longitudinal direction of the Bowden wires, but in transverse direction.
If the coupling means are to be used on the above described frame, the coupling members are joined together, or uncoupled, by a relative rotation of the frame parts.
In another embodiment deemed to be particularly advantageous, the tensioning means in the assembled condition of the two frame parts receive a force from a depressor indirectly or directly communicating with a seat post of the bicycle frame. Due to the fact that the tensioning means in the assembled condition of the two frame parts receive a force from a depressor indirectly or directly communicating with a seat post of the bicycle frame, first of all advantageously an additional safety of the connection between the two frame parts is effected by the weight of the person riding the bicycle, acting on the depressor via the seat post. Moreover the seat post may be employed as an opening lever upon separation of the two frame parts, as it were, so that opening the tensioning means for disengaging the two frame parts from each other may be effected through the greater leverage of the seat post at correspondingly lower expenditure of force. Vice versa, bracing the two frame parts when connecting them may be effected at lower expenditure of force via the greater leverage provided by the seat post. Finally in an advantageous manner, due to the fact that the seat post is in indirect or direct connection with the tensioning device, one obtains the effect that the seat post, together with the seat located therein, may in the disassembled state of the two frame parts additionally be pivoted relative to one of the frame parts, so that the stowing volume may be further reduced.
Herein the tensioning lever may moreover constitute the depressor indirectly or directly connected to the seat post of the bicycle frame.
The tensioning lever may be pivoted towards the other frame part for locking so that one contact portion thereof enters into a recess of the other frame part.
Further advantageous embodiments of the invention are the subject matters of the remaining subclaims.